<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>rem in page margin</title>
    <style>
        @page {
            margin-top: 50px;
            @top-left {
                font-size: 2rem;
                content: "This should be rendered with 2rem(=20px) font too.";
            }
        }
        :root {
            font-size: 10px;
        }
        span {
            font-size: 2rem;
        }
    </style>
</head>
<body>
<span>This text is rendered with 2rem(=20px) font.</span>
</body>
</html>